An estimated 11 to 14 million colonoscopies are performed annually in the United States, yet very limited information exists describing the impact of specific foods consumed on the days prior to the pre-colonoscopy bowel preparation. Consequently, any recommended dietary restrictions that accompany bowel purgatives are based on limited scientific evidence and vary across endoscopy units. These non-standardized dietary restrictions place constraints on people preparing for a colonoscopy and may result in decreased patient satisfaction with the procedure and perhaps decreased compliance with the preparation. If specific dietary restrictions are indeed necessary to ensure maximizing the endoscopist's ability to detect malignant or pre- malignant lesions, then identification of optimal instructions becomes an important public health endeavor. The proposed nutritional study will begin to examine, in a novel and rigorous manner, the effect of diet on adequacy of bowel preparation for colonoscopy. This study will address observed national variability in pre- colonoscopy dietary instructions and permit, for the first time, the development of evidence-based, culturally- sensitive dietary options for patients preparing for colonoscopy. A secondary aim is the validation of a novel, bowel preparation classification scale that describes colonic contents during colonoscopy. This proposed new scale was designed specifically to measure the impact of dietary interventions in the days preceding colonoscopy for nutritional research.